Spray a large mug with non-stick spray.
In a small bowl whisk together the flour, baking powder and salt. Add the milk, melted butter and splash of vanilla and stir with a wooden spoon until the dough forms a ball.
Dust your countertop or a flat surface with a little flour and roll the dough into a small rectangle with a rolling pin.
Melt 1 tbsp butter and then add 2 tbsp of brown sugar and 3/4 tsp cinnamon and stir together for the filling.
Spread the filling mixture over the dough evenly with a small spatula.
Roll the dough into a log shape and tuck the ends into the roll.
Place the dough in the bottom of the mug and shape it into a roll.
Microwave for 90 seconds. If dough is still looking moist on top microwave it again in 10 second increments until the top of the roll looks dry. *It won't brown in the microwave.
Whisk the powdered sugar, milk and vanilla in a small bowl until smooth then pour over the top of the cinnamon roll. Let it sit a couple of seconds and enjoy!
Notes: *The cinnamon roll can be inverted onto a plate after cooking and then pour the frosting over the top. *You can add raisens, chocolate chips or chopped nuts to the cinnamon roll after you spread the filling and before rolling the dough up.